This fixes PR52493 by robustifying the ptr_derefs_may_alias_p code.
It should handle being passed &MEM[0 + 0] (which is a missed folding,
to be addressed by a separate patch). The simplification code always
should recurse, we failed to do so for the &MEM_REF case.
Bootstrap & regtest pending on x86_64-unknown-linux-gnu.
Richard.
2012-03-06 Richard Guenther <rguent...@suse.de>
PR middle-end/52493
* tree-ssa-alias.c (ptr_derefs_may_alias_p): Robustify.
* gcc.dg/torture/pr52493.c: New testcase.
Index: gcc/tree-ssa-alias.c
===================================================================
*** gcc/tree-ssa-alias.c (revision 184981)
--- gcc/tree-ssa-alias.c (working copy)
*************** ptr_derefs_may_alias_p (tree ptr1, tree
*** 236,252 ****
STRIP_NOPS (ptr1);
STRIP_NOPS (ptr2);
- /* Anything we do not explicilty handle aliases. */
- if ((TREE_CODE (ptr1) != SSA_NAME
- && TREE_CODE (ptr1) != ADDR_EXPR
- && TREE_CODE (ptr1) != POINTER_PLUS_EXPR)
- || (TREE_CODE (ptr2) != SSA_NAME
- && TREE_CODE (ptr2) != ADDR_EXPR
- && TREE_CODE (ptr2) != POINTER_PLUS_EXPR)
- || !POINTER_TYPE_P (TREE_TYPE (ptr1))
- || !POINTER_TYPE_P (TREE_TYPE (ptr2)))
- return true;
-
/* Disregard pointer offsetting. */
if (TREE_CODE (ptr1) == POINTER_PLUS_EXPR)
{
--- 236,241 ----
*************** ptr_derefs_may_alias_p (tree ptr1, tree
*** 275,281 ****
if (base
&& (TREE_CODE (base) == MEM_REF
|| TREE_CODE (base) == TARGET_MEM_REF))
! ptr1 = TREE_OPERAND (base, 0);
else if (base
&& DECL_P (base))
return ptr_deref_may_alias_decl_p (ptr2, base);
--- 264,270 ----
if (base
&& (TREE_CODE (base) == MEM_REF
|| TREE_CODE (base) == TARGET_MEM_REF))
! return ptr_derefs_may_alias_p (TREE_OPERAND (base, 0), ptr2);
else if (base
&& DECL_P (base))
return ptr_deref_may_alias_decl_p (ptr2, base);
*************** ptr_derefs_may_alias_p (tree ptr1, tree
*** 288,294 ****
if (base
&& (TREE_CODE (base) == MEM_REF
|| TREE_CODE (base) == TARGET_MEM_REF))
! ptr2 = TREE_OPERAND (base, 0);
else if (base
&& DECL_P (base))
return ptr_deref_may_alias_decl_p (ptr1, base);
--- 277,283 ----
if (base
&& (TREE_CODE (base) == MEM_REF
|| TREE_CODE (base) == TARGET_MEM_REF))
! return ptr_derefs_may_alias_p (ptr1, TREE_OPERAND (base, 0));
else if (base
&& DECL_P (base))
return ptr_deref_may_alias_decl_p (ptr1, base);
*************** ptr_derefs_may_alias_p (tree ptr1, tree
*** 296,301 ****
--- 285,297 ----
return true;
}
+ /* From here we require SSA name pointers. Anything else aliases. */
+ if (TREE_CODE (ptr1) != SSA_NAME
+ || TREE_CODE (ptr2) != SSA_NAME
+ || !POINTER_TYPE_P (TREE_TYPE (ptr1))
+ || !POINTER_TYPE_P (TREE_TYPE (ptr2)))
+ return true;
+
/* We may end up with two empty points-to solutions for two same pointers.
In this case we still want to say both pointers alias, so shortcut
that here. */
Index: gcc/testsuite/gcc.dg/torture/pr52493.c
===================================================================
*** gcc/testsuite/gcc.dg/torture/pr52493.c (revision 0)
--- gcc/testsuite/gcc.dg/torture/pr52493.c (revision 0)
***************
*** 0 ****
--- 1,38 ----
+ /* { dg-do compile } */
+
+ struct Time {
+ long int sec;
+ long usec;
+ };
+ struct Flow {
+ unsigned short iif;
+ struct Time mtime;
+ };
+ struct NetFlow {
+ unsigned MaxFlows;
+ unsigned HeaderFields;
+ unsigned short *HeaderFormat;
+ };
+ static struct NetFlow *netflow;
+ static struct Time start_time;
+ static unsigned char emit_packet[1500];
+ inline long int cmpmtime(struct Time *t1, struct Time *t2)
+ {
+ return (t1->sec - t2->sec) * 1000 + (t1->usec - t2->usec) / 1000;
+ }
+ static void fill(int fields, unsigned short *format,
+ struct Flow *flow, void *p)
+ {
+ int i;
+ for (i = 0; i < fields; i++)
+ if (format[i] == 21)
+ {
+ unsigned int __v;
+ __v = cmpmtime(&flow->mtime, &start_time);
+ *((unsigned int *) p) = __v;
+ }
+ }
+ void emit_thread()
+ {
+ fill(netflow->HeaderFields, netflow->HeaderFormat, 0, &emit_packet);
+ }
